1. Our first aim is to better understand the molecular basis of DNA-protein recognition and the regulation of gene expression. Specifically, we will continue studies of the cro repressor protein from bacteriophage lambda, for which we have recently determined the three-dimensional structure. We will attempt to determine the structure of cro complexed with appropriate DNA fragments. Also, we will attempt to determine the structures of the cII gene activator protein and single-strand DNA-binding proteins, as well as complexes of these proteins with DNA. 2. Our second goal is to better understand the factors that determine the structure, stability, dynamics, folding, activity and evolution of proteins. We believe that our ongoing structural and comparative studies of phage lysozyme, goose lysozyme, thermolysin and other proteins provide a very favorable experimental framework within which to address these problem areas.